Valve actuator &amp; safety hook mechanism for vertical closing tailgate

ABSTRACT

A tailgate loading apparatus for trucks or the like that comprises an improved safety latch means operative between the frame of the tailgate and its movable lift platform so as to form a positive lock for the operating linkage when the platform is in both a raised and folded position.

United States Patent 11 1 Randall Mar. 26, 1974 [5 VALVE ACTUATOR & SAFETY HOOK 2,792,135 5/1957 Wood 214/1 P MECHANISM FOR VERTICAL CLOSING 3,269,567 8/1966 Lusash TAILGATE 3,528,573 9/1970 Denner mm P Francis R. Randall, Mount Gilead,

[75] Inventor:

Ohio

[73] Assignee: Harsco Corporation, Camp Hill, Pa.

[22] Filed: Dec. 29, 1971 [21] App]. No.: 213,471

[52] US. Cl. 214/77 P [51] Int. Cl 1360p l/48 [58] Field of Search 214/77 R, 77 P [56] References Cited UNITED STATES PATENTS 3,602,381 8/1971 Size et a]. 214/77 P Primary Examiner-Gerald M. Forlenza Assistant Examiner-Frank E. Werner Attorney, Agent, or Firm-Palmer Fultz, Esq.

ABSTRACT I 2 Claims, 4 Drawing Figures PATfNIEumzs m4 sum 1 or 3 INVENTOR. FRANCIS R. RANDALL W 54 J L ZJ A ORNEYS PATENIEU MR 26 I914 SHEET 2 [IF 3 IN VENTOR.

FRANCIS R. RANDALL BY Z AT RNEYS PAIENIEUIIARZG mm 31799373 r lO5 L 'I'IIII' INVENTOR. FRANCIS R. RANDALL VALVE ACTUATOR & SAFETY HOOK MECHANISM FOR VERTICAL CLOSING TAILGATE This invention relates to loading apparatus and particularly to an improved power operated loader adapted to be mounted on a truck or other platform to be loaded.

In general, the loading apparatus of the present invention comprises a frame means on which are mounted a pairof lift arms which in turn carry a lift platformQA power means, preferably in the form of a tion, or when it is in a folded position for road travel.

4 As another aspect of the present invention, the loading apparatus comprises apower means and manually actuated energizer that is adapted for automatic sequential operation with said safety latch means whereby said lift platform is automatically locked in position and released for movement responsive to manual operation of an actuator.

, It is, therefore, an object of the present invention to provide aloading apparatus of the type described that includes a novel safety latch means that serves to form a positive lock for the mechanism when the lift platform is'in a raised load supporting position or when it is in a folded 'storage position.

It is another object of the present invention to provide a loading apparatus of the type described that comprises a power means and manually actuated energizer that is adapted for automatic sequential operation with said safety latch means whereby said lift platform is automatically locked in position, and released for movementresponsive to manual operation of an actuatOl. 7

Further objects and advantages of the present invention will'be apparent from the following description, reference being had to the accompanying drawings wherein-a preferred form of embodiment of the invention isclearly shown.

IN THE DRAWINGS safety latch means comprising a portion of the lift apparatus of the present invention; and

FIG. 4 is another partial side elevational view of the safety latch means of FIG. 3 showing such mechanism in a released position.

to a truck frame indicated diagrammatically at 22 or other platform to be loaded.

With continued reference to FIGS. 1 and 2, the apparatus further includes a main lift arm means indicated generally at 38 which includes members 40 and 42 having their inner ends pivoted to a mounting rod 44 and their outer ends connected to a lift platform 18 at platform pivots 46. As is best seen in FIG. 2, the apparatus further includes secondary arms 28 and 30 having inner ends pivotally mounted to frame means 20 at pivots 32. It should be mentioned that the secondary arms 28 and 30 have their outer ends connected to platform pivots 48 disposed above the previously mentioned platform pivots 46 for the outer ends of main lift arm means 38.

At this point it should be mentioned that main lift arm means 38 is powered by a conventional hydraulic cylinder 50 which is pivotally connected to frame means 20 at the brackets 52 and which includes a ram 54 pivotally connected to main lift arm means 38 by a pivot pin 60 at the brackets 56.

It should be mentioned that lift platform 18 can be moved -to a closed position, not illustrated, for road travel. This is done by lowering the platform to the ground, manually folding it in a counter-clockwise manner to a vertical position, and then powering it up whereby the platform continues to fold to a storage position under the truck bed.

Reference is next made to the novel safety latch means which is best seen in enlarged relationship in FIGS. 3 and 4. This mechanism comprises a first latch element or hook 94 which is pivotally mounted by a pin on-a bracket 118 supported by transverse frame member 97, said bracket and frame member comprising a portion of the previously mentioned frame means 20.

The mechanism comprises a second latch element or pin 108 mounted on main lift arm means 38 by means of a bracket 109 supported by a collar 111 on cross member 112 with the collar being welded on the cross member when the apparatus is mounted on the truck so as to position latch element or pin 108 in the proper location to latch when the platform is in the raised position of FIG. 1.

It should be mentioned that latch element or hook 94 is normally urged toward the latched position of FIG. 3 by a tension spring 93 operatively connected between transverse frame member 97 and hook 94.

With reference to FIGS. 1, 3 and 4, latch element 94 is moved from the closed position of FIG- 3 to the unlatched position of FIG. 4 when the operator manipulates a control lever 137 by moving it to the right as viewed in FIG. 1.'

When control lever 137 is moved to the right, a transverse control rod 134 is pivoted so as to swing lever 132 to the left thereby extending the control rod 102. Such action shifts link 96 to the left thereby lifting hook or latch element 94 away from latched engagement with the other latch element 108.

AT the same time, control lever 137 is actuated to disengage the safety latch means as described above, a control valve 101 for powering lift platform 18 is simultaneously actuated by moving valve control arm 104 to the left. This energizes hydraulic cylinder 50, by suitable hydraulic lines not illustrates, so as to lower lift platform 18 from the upper load delivering position of FIG. 1 to a lower load receiving or ground position.

With continued reference to FIGS. 1, 3 and 4, when control lever 137 is manipulated in the other direction to raise the platform, that is to the left as seen in FIG. 1, then hook or latch element 94 is returned to the latchable position of FIG. 3.

At the same time valve arm 104 is shifted to the right, as viewed in FIG. I, so as to operate valve 101 and thereby deliver pressurized hydraulic fluid to the other end of hydraulic cylinder 50 so as to move lift platform 18 from the ground or load receiving position upwardly to the load delivering position of FIG. 1. As this occurs, main lift arm means 38 pivots upwardly and moves latch element or pin 108 up into engagement with outer latch surface 113. This moves the latch element 94 slightly upwardly and permits pin 108 to latch into recess 110.

It should be mentioned that link 96 is provided-with a lost motion slot 100 so as to permit free movement of lost motion pin 98 in slot 100 thereby permitting the pin latch element 108 to cam itself into the latched recess 110 of latch element 94.

It should be mentioned that with the safety latch means engaged, as seen in FIG. 1 and 3, the lift platform 18 can be left in the elevated position of FIG. 1 for extended periods of time, even when heavily loaded, without having the lift platform 18 gradually creep down due to any slight leadage which might be present in the hydraulic system. For example, if the lift platform is left for extended periods of time in an upper loaded position, it is possible for leakage of fluid to occur past the piston in power cylinder 50 or past the sealed surfaces within control valve 101 due to biasing forces imposed by loaded lift platform 18. With the safety latch means, however, it will be understood that lift platform 18 is positively mechanically locked in the raised position.

I claim:

1. A loading apparatus comprising, in combination, frame means adapted to be attached to a platform to be loaded; lift arm means including an inner end pivotally connected to said frame means and an outer end; a lift platform pivotally mounted on said outer end of said lift arm means; power means for swinging said lift arm to raise an lower said lift platform between upper and lower positions; secondary arm means including an inner end pivotally connected to said frame means and an outer end pivotally connected to said lift platform; safety latch means including a first latch element mounted on one of said arm means and a second latch element movably mounted on said frame means; valve means for delivering pressurized fluid to said power means and including a pivotally mounted valve actuating arm; a link including a first connection with said valve actuating arm and a second connection with said second latch element; a manually actuated control lever for operating both said second latch element and said valve actuating arm; and a control rod having a first end connected to said valve actuating arm and a second end connected to said control lever.

2. The apparatus defined in claim 1 wherein said link includes a lost motion connection permitting movement of said valve actuating arm, in one direction independently of said second latch element. 

1. A loading apparatus comprising, in combination, frame means adapted to be attached to a platform to be loaded; lift arm means including an inner end pivotally connected to said frame means and an outer end; a lift platform pivotally mounted on said outer end of said lift arm means; power means for swinging said lift arm to raise an lower said lift platform between upper and lower positions; secondary arm means including an inner end pivotally connected to said frame means and an outer end pivotally connected to said lift platform; safety latch means including a first latch element mounted on one of said arm means and a second latch element movably mounted on said frame means; valve means for delivering pressurized fluid to said power means and including a pivotally mounted valve actuating arm; a link including a first connection with said valve actuating arm and a second connection with said second latch element; a manually actuated control lever for operating both said second latch element and said valve actuating arm; and a control rod having a first end connected to said valve actuating arm and a second end connected to said control lever.
 2. The apparatus defined in claim 1 wherein said link includes a lost motion connection permitting movement of said valve actuating arm, in one direction independently of said second latch element. 